Description from Flora of China
Annuals, sometimes biennials. Stems diffuse, ca. 10-20 cm tall, 20-50 cm, densely pubescent with multicellular hairs often more densely so along 2 lines. Opposite leaves in (2 or)3 or 4(or 5) pairs; petiole 1-8 mm; leaf blade ovate-lanceolate to suborbicular, (6-)10-20(-25) X (5-)8-15(-20) mm, evenly sparsely pubescent on both surfaces, margin flat, obtusely crenate-serrate, 3-6(-10)-toothed per side. Racemes terminal, lax, very long; bracts alternate, leaflike, petiolate, uppermost ones smaller than others. Fruiting pedicel (1.2-)1.5-3(-4) cm, usually longer than bract. Calyx 4-lobed; lobes ovate-lanceolate, 5-8(-10) X 2.5-3.5(-4) mm in fruit, sparsely pubescent, veins 3. Corolla usually blue, rotate, 0.8-1.4 cm in diam., throat sparsely hairy; lobes ovate to orbicular. Stamens slightly shorter than corolla. Capsule obcordate, strongly compressed, 4-6 X 6-9 mm, apically notched at right to obtuse angle; lobes obtuse, glandular hairy, venation conspicuously reticulate. Style 2-3 mm, exserted. Seeds slightly navicular, usually 1.4-2.3 X 0.9-1.6 mm; seed coat deeply rugose dorsally. Fl. Mar-May. 2n = 28.
Naturalized in waste fields and roadsides; below 1700 m. Anhui, Fujian, Guangxi, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Taiwan, W Xinjiang (Yining Xian), E Xizang, Yunnan, Zhejiang [native to SW Asia and since the 19th century spread over most of the world].